Jethro,
It sounds like your vacuum motor is in need of a rebuild. Could also be something under the dash binding up the wiper arms, but most likely culprit is the motor.
There are tons of previous conversations about the topic with helpful info and sources should you decide to tackle it yourself or send it out for rebuild.
On the flip side, there are also electric units designed to replace the vacuum system. On those, it beneficial to not go cheapest. Some products are a major pain, while others are well designed and function perfectly.
Your choice on which direction to pursue.
